Routine vaccination for influenza and pneumococcal disease and its effect on COVID-19 in a population of Dutch older adults

Abstract

Objectives: Protective heterologous beneficial effects of vaccines have been reported, and in this study we aimed to assess the impact of routine pneumococcal and influenza vaccination on the incidence and symptom duration of COVID-19 in a population of Dutch older adults. Methods: This cohort study is a secondary analysis of the BCG-CORONA-ELDERLY study, a randomised controlled trial on the effect of BCG vaccination on the cumulative incidence of respiratory tract infections requiring medical intervention in adults ≥60 years. The primary outcome was the cumulative incidence of a self-reported positive SARS-CoV-2 PCR test, and was assessed using a Fine-Gray competing risks model adjusted for baseline characteristics at enrolment. We analysed data from November 1st 2020 until the end of the main study in May 2021. Results: Routine vaccination data 2020/2021 were available for 1963/2014 (97.5 %) participants; 44/1963 (2.2 %) were excluded due to COVID-19 before vaccination. 1076/1919 (56.1 %) had received the influenza vaccine and 289/1919 (15.1 %) the pneumococcal vaccine. The cumulative incidence of COVID-19 was 0.030 (95 %CI 0.021–0.041) in those vaccinated against influenza compared to 0.029 (95 %CI 0.019–0.041) in the unvaccinated group (subdistribution hazard ratio (SDHR) 1.018; 95 %CI 0.602–1.721). For pneumococcal vaccination the cumulative incidence was 0.031 (95 %CI 0.015–0.056) for the vaccinated and 0.029 (95 %CI 0.022–0.038) for non-vaccinated individuals (SDHR 0.961; 95 %CI 0.443–2.085). BCG vaccination in the previous year and sex were not significant effect modifiers in the primary analysis. Duration of fever, cough and dyspnoea was also not significantly different between treatment arms. Conclusion: Neither influenza nor pneumococcal vaccination was associated with a lower incidence or shorter duration of COVID-19 symptoms in older adults.